CORS Preflight Fails

  • 7 December 2021
  • 1 reply


We are experiencing some CORS issues, we have 2 mixpanel projects, one representing development data and one for production purposes.

On the DEV environment all is working fine, we track events in ReactJS using the JS api. 

On the PROD environment we experience CORS issues.
Method xhr is not allowed by Access-Control-Allow-Methods in preflight response.

I already checked the browser settings for adblockers, all is disabled.

There is one difference, when logging to DEV project, the url is… on the PROD project logging goes to


Any thoughts on getting this solved?


Kind regards



Best answer by alon 10 December 2021, 08:48

View original

1 reply

Badge +1


This sounds like a devops issue. Did you check with your team on how the dev and prod servers are different with accepting CORS?

If this is not the case I suggest opening a ticket to our support that might be able to assist you.